Mackerel belong to the large
family of marine fishes known as the Scombridae.
It is one of the smaller fishes of the family that includes the tunnies
and the well known Skipjack Tuna. All members are streamlined predatory
fish, supremely designed to cleave through water, with the absolute minimum
of protuberances to offer resistance to their swift passage. Its speed
can reach 100 metres in 11 seconds (20.336 mph).

The Atlantic Mackerel is
by far the commonest of the 10 species of the family that have been caught
in British waters. It is extremely common in huge shoals migrating towards
the coast to feed on small fish and prawns during the summer. Overfishing
has reduced the numbers in parts of the North Sea.

Mackerel are found off all
British coasts, in the Mediterranean Sea, and on the American side of the
north Atlantic.

Two distinct stocks have
been identified in British waters, one spawning in the North Sea, and the
other spawning to the west of the British Isles.

Healthy fish are coloured
an iridescent blue-green on the back, with curved black lines. Lengths
of up to 66 cm (26 in) have been recorded, but 40 cm (16 in)
is more usual. Fish over 680 g (1 lb 8
oz) are considered
large.

When freshly caught, the
mackerel makes excellent eating, but the flesh deteriorates rapidly. A
similar species, the Spanish Mackerel, Scomber japonicus, is found
in the English Channel during the summer. Both species are distinguished
by five small finlets between the second dorsal and tail fin, and a further
five finlets between the anal fin and the tail.

At spawning time, the eggs
and sperm of the mackerel are released into the sea. Mackerel can release
up to one million eggs. The egg is just over 1 mm long, with an amber
oil globule that keeps it floating in the pelagic surface waters. Surviving
larvae at 3 mm long will feed on copepods. By the first autumn, the North
Sea population of Mackerel will attain a length of 15 cm, reaching 25 cm
after one year.

Stomach content analysis
of adult mackerel sampled in Loch Ewe and the Minch (Scottish seas) during
the summer months indicates a variety of prey including small fish such
as sand-eels, Ammodytes spp., small gadoids (cod family), and clupeoids
(herrings), as well as filter feeding for small crustaceans such as Euphausids.

Small creatures exceeding
1.5 mm can be sieved from the water in close-set gill-rakers. This can
occur when the fish swims at speeds in excess of 0.7 body lengths per second.
Gill ventilation (breathing) occurs by a method known as "ram ventilation"
and the cessation of the normal buccal/opercular pump system. Its speed
may reach 25-30 body lengths per second.

In Sussex waters, mackerel
are known to feed on juvenile prawns of the species Palaemonserratus,
about 10 mm long, in large numbers.

Feeding ceases when the mackerel
return to deeper water during the winter.

Mackerel are long-lived fish,
if they are not caughty, and fish of over 25 years old have been caught
in the North Sea.

The largest Atlantic Mackerel
ever caught on rod and line was from deep water off the western Swedish
coast (Svaberget) and weighed 3.074 kg (6
lb 13 oz), (1995).

7 February
1998: Mackerel, Scomber scombrus, are being caught in commercial
numbers off Brighton, Sussex. These fish are normally caught only in summer.
Fishermen believe that the warm water is the reason for their occurrence,
although in the coldest month of the year the sea temperature was measured
at 7oC which is about normal for February. Report by Peter
Talbot-Elsden.Recommended
reading:

The
Mackerel by Stephen LockwoodDr
Lockwood took over the UK's mackerel research programme at a critical time
and this enables him to give a unique review of events which led to the
revival of the English mackerel fishery in the 70s.

Why
the interest in mackerel?; The mackerel and where it is found; Early development
of the European mackerel fisheries; Mackerel fisheries since the mid-1960s;
Stocks and migrations; Reproduction and early life-history; Age, growth
and maturity; How big is the resource?; When, where and how mutch should
we catch?; Scientific advice and fisheries management; Conflicts of interest;
Discarding and conservation; An international management measure; Catch
limitation; Recent results and stock prognosis.